Tree shade reduced wall surface temperatures by up to 9?¡ãC and external air temperatures by up to 1?¡ãC. The smaller trees did little to reduce external wall surface temperatures, and moving the tall trees further away from the building wall eliminated their cooling benefits. Wall surface temperatures were best predicted by shade cover and solar irradiance, and was most poorly predicted by shading coefficients, that varied greatly through the day and the season, as tree height and leaf area index increased.
Trees can reduce external solar irradiance loads when they are close enough and tall enough to shade the majority of the wall. To simulate the thermal performance benefits that trees provide, it is necessary to account for seasonal, growth and phenological changes in tree shade amount and quality.